This invention pertains to a special, self-healing, anti-liquid-leakage projectile barrier structure, and to a related methodology. In particular, it pertains to specific, improved and now recognized forms of the layered barrier structure described in the '723 patent application.
While there are many applications and situations wherein the present invention offers important utility, a preferred and best mode embodiment of, and manner of practicing, the invention are described herein in the setting of an intended disabling projectile attack, such as a sniper bullet attack, on the otherwise exposed fuel tanks in certain types of military vehicles. Although this military environment provides an excellent vehicle for describing the present invention, those skilled in the art will quickly understand from the disclosure herein how the structure and methodology of the invention may be employed with respect to other types of liquid-containing structures (i.e., ground storage tanks, pipelines, etc.).
With respect to this illustrative military use of the present invention, a tactic employed in combat involves directing sniper fire at a vehicle's exposed fuel tank or container. Bullet penetration of such a fuel tank initiates fuel leakage when a puncture occurs, and successful sniper fire which has achieved a puncture in such a tank may then be followed by the firing of incendiary rounds which ignite a catastrophic and life-threatening fire.
According to the present invention, a selected exposed surface of such a tank, or container, is appropriately coated with a multi-layer (and as proposed by the present invention, preferably three-layer), self-healing/self-sealing barrier structure which lies at the heart of the present invention. This layer structure is “sandwich-like” in form. It includes two, outer bracketing layers formed of a high-elastomeric material, with a third, intermediate layer formed as a composite-material layer having a body made of the same high-elastomeric material used in the outer layers, and imbedded within this body, a distribution of bead-like elements (called beads herein) which respond to contact with the usual hydrocarbon fuel to undergo rapid absorption of any leaking fuel, accompanied by rapid, three-dimensional physical enlargement as a consequence of such liquid absorption.
Preferably, the elastomeric material just mentioned is capable, within its range of elasticity, of easily undergoing about a 400-percent stretch. A very suitable material for this purpose is a two-part, bendable product sold under the trademark TUFF STUFF®, and made by Rhino Linings USA, Inc. in San Diego, Calif. Specific product designations for such a two-part Rhino-Linings product are 60012 and 60058.
With respect to the mentioned distribution of bead-like elements, a very suitable material takes the form of what are referred to as liquid-imbiber beads which react to hydrocarbon fuel in the manner mentioned above, and which are made by a company known as Imbibitive Technologies America, Inc. in Midland, Mich. A particular liquid-imbiber-bead product made by this company, and very suitable for use, is a product which is sold under that company's product identification IMB230300.
Those skilled in the art will certainly recognize from the description given below how different, specific elastomeric materials and imbiber, bead-like elements may be selected and used for different kinds of potential liquid leakage.
The present invention specifically focuses upon improved layer-thickness configurations for the basic barrier structure innovation described in certain ones of the above-cross-referenced, prior patent applications. Very specifically, and referring to one preferred form, or embodiment, of the present invention, we have discovered that, within certain ranges of composite-layer thicknesses, a very successfully performing multi-layer (i.e., composite-layer) arrangement includes two outer (innermost and outermost bracketing layers) high-elastomeric layers which possess a common thickness which is substantially twice that of the intermediate composite layer. We have found that a very appropriate range of thicknesses useable for the two outer elastomeric layers is about ¼-inches to about ¾-inches, and that an appropriate related range of layer thicknesses for the intermediate composite layer is about ⅛-inches to about ⅜-inches. With respect to the military-situation conditions described above herein, we have further found that a preferred layer organization is one wherein there is a common layer thickness for each of the two outer layers in the composite, plural-layer structure of the proposed barrier structure, which common thickness is about ¼-inches, with the intermediate composite layer having a thickness of about ⅛-inches.
Another discovery about an improved form of layer arrangement involves a plural-layer composite structure wherein, regardless of innermost layer thickness, so long as that thickness is about ⅛-inches, the outermost layer thickness is about twice that of the intermediate layer thickness. For example, we have found that, for certain applications, this other, preferred, composite layer arrangement can be realized with an innermost layer thickness of about ⅛-inches, an intermediate layer thickness in the range of about ⅛-inches to about 3/16-inches, and an outermost layer thickness (preferably in a 2:1 ratio with the thickness of the intermediate layer) in the range of about ¼-inches to about ⅜-inches, and with an overall composite layer thickness preferably being no less than approximately ⅝-inches.
The various features, advantages, and operating mechanisms which characterize the present invention will now become more fully apparent as the description which follows below is read in conjunction with the single accompanying drawing FIGURE.